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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0fbdd8376405ce1a6fb915425fccb66b4ddbc5d81ba0f8a29bb75d2c09b3ab7' 
  AND token = 'UsFATUnEqSqhSTimpW4isHTq8vYCV1JPYuXMgDI+cdY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}