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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6c9326aaa076d56cdfdf7e1669dc0f46d781fd2e03ef3f3b13e29c0c800caa3' 
  AND token = 'IaT8nuk4vjJUN/OPTyDewnex4D+Vgv2eAqkTnTM3gGA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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