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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ddcfa0d6ef2dde8cf7b9c2357be2a50c3819d09e8141284d58e4b22de5dcac21' 
  AND token = '3LF7KXY7rhz3pmUcnPxnkPchFPeQPcFuS/qiLLUIIbM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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