SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f74f8a045b2ce5d719f336049692d6169ccad08e676a1ff1987bb5550f4f123' 
  AND token = 'gBv4eaG3Qg6B3ltpYKM3SuvQii9d/V/5+WSrRwHddU4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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