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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1f3e4d3cbd9aadc7d2697e1ba0ee8914b0a00240ea26d1a3fef4d055a91979e' 
  AND token = '6Xs0573WrONC8EcOzKhkB1g+ALfyV3KfaCI+zpBhb3M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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