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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12bb29dfa2cba63a39fcfdca52a730fc154187c7c0d63c7149d2f90d7a318a25' 
  AND token = 'gt+EiMXiSfZyQKbwydq/1FsSJr9CMOR51x/HIxGXgtg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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