SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e51199f7badfc1e36467d310d98675f6b9dd610d55bc2b6c98b8a2aa480fb8a' 
  AND token = 'o310Sz97pcFntK+W2cfVsgdxCDGv/lHIGPCguKzw5VI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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