SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77b15a5be0f512c532931982ec5cd9d4cf5e65909fc56234fdbd75875f30f61b' 
  AND token = 'iWZVGv4thdtCGlPST4x5IP9gOvn2rLj3ylJ/si4ewz8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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