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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4ad23d0d21d1cbe163fe2bb688a8d780722faefeb6ada47abcb94b0dbd01dd5' 
  AND token = '4TFfAcl/TKf6i7HrGZdYA3wZUq43giqwyMFrb1ytrdI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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