SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c8ff33605c21a899677ee407c0a4dc508d14eff699dcbf16a514007f7d0266e' 
  AND token = 'hhWXZNst+rz3n6QefISWKrlB3L5tdQfQOTk3igldbGM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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