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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '3e1c9ad80f4df62cfa4236cee89a5656ec90bff83a1bb2e4dc3dba372a142b2c' 
  AND token = 'Am39B84LAlIDe0Hd6i2VGDbCUyGlmLrhx9oeRoHq1fk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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