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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8174d15d4afd018befb37db05592d6b27384bb3de9a09fbaaf92fc57ed83e08' 
  AND token = 'brSihgw/Oa6pj9x0hkWt9M8hTCP8V0O+LrgWVmj/Kcs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}