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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef550a9cfaffb33bdde104cea16ac9f4c449e3ed2d5f5675bc5446f04ff9f8f0' 
  AND token = 'X4DfnI9A3P8aXU6tDcqJlqbn06KICZy+e55+Tgr9Qig=' 
  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"
    }
  }
}