SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8521589e23f036a353f390c2ee3a3d7dfce4928abb6a627a74263a53e092860' 
  AND token = 'Mg9tr8qMFK4/yVBGtfju8coU+Mycj0DYBgauOPmP6iM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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