SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '887d6338d398f3a8b00c02a79951d6cca96f98b0247bb8ff8eff45337e32bc47' 
  AND token = 'inqACveqxYddK8LhjztRhfYGFCZFAcno3wE6UE9BL+I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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