SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75fe6f70219a5d66fdc9b6d4b901cf9aa2819a915448a9c1995b17152c5c0e82' 
  AND token = '/1pFhn2SEPUC+1L4IC1WKS9OMYOBbGktwW8nDHpAY7U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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