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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e78d21a499eb6fc68f681b976f3cbb819c10566025949f78071fca8da18ac6eb' 
  AND token = '+L93m9wiKhqjuVFO3VzKTdNrw4kXALg0SkcdTf04d3k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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