SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da873d1f4a6b5709cd7069085411f9d75856be18fc75d686fd608221797b3052' 
  AND token = 'B2ruHaD1fUYFG6h6gjnYv//62eTWkhexrANZHILErjw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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