SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2d96540bc030b5be18f75d5f29cbd0f4e903a1f99118ffd0b70fe9b1aa2253fb' 
  AND token = 'ZAQMInKU33z3zQffZ3mlJwRhSTmMb5INC8+p6muJf0Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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