SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3a70cb64249a7950662866d650382ba2c86f733a92bccd2c47118672d3fbfa1' 
  AND token = 'o1uqWKxGYKyJpx2mVsiTT3tukBzow1CFb5xWeB4zkrQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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