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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5047768bf97fd9ed8a3769825169686ce6d1f5db30a0418a492f8e8192d5d921' 
  AND token = 'culkcBLbew8ZP4ytU5UOIu9RQzMK0aBtL4Qy8/d40xc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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