SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c50f4219319ff934e9be550092c21d867d79562857e11a578f5ce66325b3d8f6' 
  AND token = 'alrllqYkgNP0O4cYPzEZFfhCJQ3GCQLPAFgbE5qih5M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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