SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ddc686175ed30cd04d393304c4b7a28f5c55877dbcf68437247f8a38cd690a78' 
  AND token = 'rmx1l+i6cVq8YjBhB1Bd/mvsTFdWPB+mHekp+z2Cm+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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