SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '155fa0e7ac1c64419aedbf5d2227eba9f031bae9557138b6a4a05a2ea42b2b5a' 
  AND token = '4ow0Qk3gAw0vdcfCBo6rcs4urSN2HYhe/Aw7PkbE0qg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}